Method for suppressing or treating drug-induced nephropathy

ABSTRACT

The present invention provides a novel drug for relieving drug-induced nephropathy and acute hepatopahy containing a midkine (MK) family protein such as pleiotrophin (PTN). The MK family proteins can inhibit nephropathy induced by an antitumor agent or acute hepatopathy caused by carbon tetrachloride and thus effectively relieve drug-induced nephropathy or hepatopathy.

TECHNICAL FIELD

The present invention relates to drugs for relieving drug-induced nephropathy and hepatitis.

BACKGROUND ART

The use of drugs for therapeutic and/or diagnostic purposes has increased year by year, and the drugs used have diversified. These drugs can provide us significant benefits but can also cause substantially harmful effects, especially to kidneys, due to their specific functions described below.

Kidneys weigh less than one percent of the total body weight. From a physiological viewpoint, 25 percent of the total cardiac output flows into the kidneys; 150 liters of primitive urine, up to 50 times the total blood plasma, is filtered through glomeruli per day; and final urine is made by reabsorption, secretion, and metabolism through uriniferous tubules variable in structural and functional heterogeneity. Thus, drugs or their metabolites in blood always circulate, and these substances are concentrated and metabolized in kidneys. Consequently, various highly concentrated metabolites, including original drugs, are distributed in kidneys. Kidneys are likely to be frequently and intensively exposed to drugs. Four types of drugs may induce nephropathy: antimicrobial agents, nonsteroidal agents, contrast agents, and antitumor agents.

The liver can also be easily damaged by drugs. Drug-induced hepatopathy is classified by its onset mechanism into toxic hepatopathy caused by direct attack of drugs or their intermediate metabolites to the liver, and allergic hepatopathy caused by allergic response, type IV delayed allergic response in which T cells are involved. Drug-induced hepatitis is caused by, most frequently, antibiotics, followed by drugs for the central nervous system, drugs for circulatory organs, antitumor agents, hormonal agents, diagnostic agents, etc.

Attempts have been made to relieve drug-induced disorders by using γ-globulin, cytochrome C, adenine, SH compounds, vitamin B group, etc., but they are not sufficiently effective. It is very important to clinically cure drug-induced disorders (side effects) because of the interruption of the treatment and the importance of patients' quality of life (Q.O.L.).

DISCLOSURE OF THE INVENTION

An objective of the present invention is to drugs that effectively relieve or suppress disorders induced by various drugs, especially by antitumor agents.

The inventors have focused on the facts that proteins belonging to the midkine (MK) family such as midkine (MK) and pleiotrophin (PTN) are growth and differentiation factors with multiple functions. The functions include 1) elongation of neurite, 2) activation of fibrinolytic system, 3) strong expression in human cancerous areas, and 4) cure of wounds. Numerous studies have been performed on such proteins in order to find novel pharmaceutical effects.

Midkine was discovered as a product of the gene whose expression was induced in the early stage of the differentiation process with retinoic acid in mouse embryonic tumor cells (Kadomatsu, K. et al., Biochem. Biophys. Res. Commun., 151: 1312-1318, 1988). Pleiotrophin was discovered in the brain of a newborn rat as a heparin-binding protein with neurite elongation ability (Rauvala, H., EMBO J., 8: 2933-2941, 1989). Midkine and Pleiotrophin form a novel class of growth and differentiation factors as heparin-binding proteins. They exhibit 45% homology and are collectively called the MK family (Muramatsu, T., Int. J. Dev. Biol., 37: 183-188, 1993; Muramatsu, T., Develop. Growth & Differ. 36(1): 1-8, 1994). Midkine and Pleiotrophin each exhibits a specific expression pattern in development processes, and is expected to be involved in important physiological activation in differentiation.

The inventors found that MK inhibits cell death caused by antitumor agents in vitro and that MK gene relieves disorders induced by an antitumor agent from the results of an experiment in which an antitumor agent was administered to knockout mice in which MK gene was functionally destroyed. The inventors also found that administering MK or PTN to wild mice relieves the disorders caused by antitumor agents, to complete the invention. The present invention encompasses each invention described in the claims.

In this invention, knockout mice provided an opportunity to investigate how MK gene in the living body fights against disorders caused by drugs and to analyze how each knockout mouse responds to the forced administration of MK at the individual level. Details of MK's function and mechanism are presently not clear. If MK functions as a trigger protein for the functional cascade of cytokines or growth factors, a very small amount of MK is presumably needed, and the use of knockout mice becomes more important. Recently, a cell surface receptor specifically binding to MK with high affinity (molecular weight 250+kDa) has been discovered. Its characteristics imply that autocrine stimulated by MK in tumor cell proliferation could be mediated by the receptor and would activate the JAK/STAT pathway (Edward, A. R. et al., J. Biol. Chem. 273: 3654-3660, 1998).

To clarify the relationship between MK and ontogenesis, homozygous MK gene-knocked out mice in which parts of exon 2 and exon 3 are damaged as illustrated in FIG. 1 were prepared (Biochemistry 7, Heisei 8: Volume 68, pp. 1239, 4-P-1244). Those knockout mice did not die during the fetal period and weighed significantly less than heterozygous or wild types (Biochemistry 7, Volume 68, pp. 1239, 4-P-1244, 1996).

Antitumor agents were administered to the knockout mice (simply referred as knockout mice) and wild mice. Survival rate, blood urea nitrogen (BUN) level, and creatinine level of each mouse were compared as indices of disorders after the administration to monitor the ability of MK gene in the living body to relieve disorders caused by antitumor agents. BUN and creatinine levels can be used as indices of functional disorders in kidneys because urea is accumulated in blood due to the reduced renal excretory ability.

In this invention, cisplatin was administered to the knockout mice and wild mice, then BUN level and survival rate were compared. The BUN level of the knockout mice were significantly higher than that of the wild mice. The survival rate of the knockout mice also differed significantly from that of wild mice. The death rate of knockout mice increased by the seventh day after the administration. The rate of abnormal BUN levels in knockout mice that had been forcedly administered MK was significantly lower than that in the group that had been administered physiological saline by the third day after the administration. The effectiveness of MK in suppressing renal cell disorders caused by cisplatin was confirmed by conducting an experiment in vitro using human infantile renal cancer cell lines. An experiment using the wild mice revealed that MK relieved acute hepatopathy due to carbon tetrachloride, and that both PTN and MK effectively suppress nephropathy caused by cisplatin.

These results indicate that proteins of this invention belonging to the MK family effectively relieve or suppress drug-induced nephropathy and hepatopathy.

MK protein (simply referred to as MK) used as an effective ingredient of the pharmaceutical composition of the invention is described in the following references (human MK gene, unexamined published Japanese patent application (JP-A) No. Hei 5-91880; sequences of the human MK gene and protein, JP-A No. Hei 6-217778; MK protein, JP-A No. Hei 5-229957; Muramatsu, T., Develop. Growth & Differ. 36(1), 1-8, 1994). PTN protein used as an effective ingredient of the pharmaceutical composition of the invention is described in the following references (Muramatsu, T., Develop. Growth & Differ. 36(1), 1-8, 1994; Kurtz, A. et al., Critical Reviews in Oncogenesis, 6(2):151-177, 1995). FIGS. 11 and 12 show the amino acid sequence of PTN and MK proteins, respectively. The proteins belonging to the MK family and used as effective ingredients of the pharmaceutical composition of this invention include natural proteins derived from humans, mice, or other mammals, or artificial proteins manufactured by chemical synthesis or genetic engineering. Also, the proteins of the invention that belong to the MK family include proteins or polypeptides which do not cause any changes of the above-described biological activities and differ from proteins derived from nature in the number or the sequences of amino acids. Specifically, the present invention includes proteins corresponding to natural proteins in which the amino acid sequence of natural proteins is partially deleted or replaced by other amino acids, or other amino acids or polypeptide of different length are inserted or added. Amino acids to be replaced or inserted are not limited to natural types.

The expression system using E. coli (Studier, F. W. & Moffatt, B. A., J. Mol. Biol. 189: 113-130, 1989; Studier, F. W. et al., Meth. Enzymol. 185: 60-89, 1990) or the expression system using baculovirus (O'Reilly, D. R. et al., Baculovirus Expression Vectors, A Laboratory Manual, Oxford University Press, 1992, Ausubel, F. M. et al. eds., Current Protocol in Molecular Biology, Unit 16.11, Wiley Interscience, 1994) can be used to obtain the MK family proteins that are effective ingredients of the invention using genetic engineering techniques. The inventors employed the expression system using methyl alcohol dependent yeast Pichia pastoris to obtain the MK proteins (refer to JP-A No. Hei 9-95454).

The pharmaceutical composition of the invention contains the MK family protein in an amount effective to prevent or treat nephropathy or hepatopathy caused by drugs. The effective ingredients of the invention can be prepared in a desirable dosage form by mixing with usually used pharmaceutically acceptable carriers, vehicles, diluents, preservatives, stabilizers, buffers, etc.

The pharmaceutical composition of the invention can be administered orally or parenterally. Dosage forms for oral administration include tablets, granules, and capsules. Dosage forms for parenteral administration include injection, suppositories, or percutaneous agents, which are administered intravenously, subcutaneously, intramuscularly, or intraperitoneally.

Physiologically active peptides such as MK or PTN are rapidly digested by protease in digestive tracts in general when they are administered orally. To stabilize MK or PTN in vivo, a hybrid MK or hybrid PTN should be prepared by binding it to water-soluble macromolecules (for example, polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP)). Hybrid constructions of IL-6, TNF-α, etc. have been attempted, and the function has been enhanced by selecting the most suitable hybrid condition (Tsutsumi, Y. et al., Br. J. Cancer. 74: 1090-1095; Tsutsumi, Y. et al., Thoromb. Haemostasis, 77: 168-173, 1997; Tsutsumi, Y. et al., J. Control Release, 33: 447-451, 1995).

The MK family proteins that are effective ingredients of the pharmaceutical compositions of the invention vary depending on the dosage of the causative drug, severity of nephropathy or hepatopathy, age, sex, and weight of the patient when used to prevent or treat nephropathy or hepatopathy caused by drugs. The proteins of the invention can be administered once or several times at a dosage of 1 μg/kg to 100 mg/kg of body weight per day.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the mutant chromosome of the knockout mouse in which parts of exons 2 and 3 of MK gene of 129/Sv mice was destroyed.

FIG. 2 shows the survival rate of 129/Sv MK knockout mice and that of wild mice after the administration of cisplatin.

FIG. 3 shows blood urea nitrogen of 129/Sv MK knockout mice and that of wild mice on the day of administration and on the third and fifth days after the administration of cisplatin.

FIG. 4 shows the frequency of abnormal blood urea nitrogen of 129/Sv MK knockout mice on the day of administration and on the third and fifth days after 14 mg/kg cisplatin was administered and MK or physiological saline absorbed capsules for sustained release were intraperitoneally implanted.

FIG. 5 shows the serum GOT of mice suffering from acute hepatopathy caused by carbon tetrachloride when various concentrations of MK or physiological saline were administered to the mice.

FIG. 6 shows the serum GTP of the same mice as in FIG. 5.

FIG. 7 shows the survival rate of G401 cells where 2×10⁴ cells/well were cultured in the medium alone, the medium with 2 μg/ml of MK, or the medium with 10 μg/ml of MK, and treated with briplatin (cisplatin) during the culture.

FIG. 8 shows the survival rate of G401 cells (6×10⁴ cells/well) after the same treatment as in FIG. 7.

FIG. 9 shows BUN levels before and after the administration of briplatin (cisplatin) to mice during the administration of PTN or physiological saline.

FIG. 10 shows the serum creatinine of the mice in FIG. 9.

FIGS. 11A-E shows the amino acid sequence of PTN proteins. FIG. 11A shows the sequence from human (SEQ ID NO. 1). FIG. 11B shows the sequence from mouse (SEQ ID NO. 2). FIG. 11C shows the sequence from rat (SEQ ID NO. 3). FIG. 11D shows the sequence from bovine (SEQ ID NO. 4). FIG. 11E shows the sequence from chicken (SEQ ID NO. 5).

FIGS. 12A-D shows the amino acid sequence of MK proteins. FIG. 12A shows the sequence from human (SEQ ID NO. 6). FIG. 12B shows the sequence from mouse (SEQ ID NO. 7). FIG. 12C shows the sequence from chicken (SEQ ID NO. 8). FIG. 12D shows the sequence from Xenopus laevis (SEQ ID NO. 9).

BEST MODE FOR IMPLEMENTING THE INVENTION

The present invention is illustrated in detail below with reference to examples, but is not to be construed as being limited thereto.

EXAMPLE 1 Effect of MK on Relieving Nephropathy in Vivo

The 129/Sv knockout mice in which parts of exons 2 and 3 of MK genes were destroyed as illustrated in FIG. 1 were used (Biochemistry 7, Volume 68, pp 1239, 4-p-1244, 1996; Nakamura, E. et al. Genes to Cells 3, 811-822, 1998). FIG. 2 shows the survival rate of the 129/Sv MK gene-knocked out mice and that of wild mice after the intraperitoneal administration of 14 mg/kg cisplatin (product name, briplatin, Bristol Myers Squibb Company). FIG. 3 shows BUN levels 0, 3, and 5 days after the administration of the cisplatin. Cisplatin was selected because it is the fastest, most effective, and most common antitumor agent against solid tumors. Moreover, the side effect of cisplatin is nephropathy such as acute renal failure and MK is expressed only in kidneys in adult mice.

The Student t test revealed that the BUN levels of knockout. mice were significantly higher than that of wild mice, as indicated in FIG. 3.

FIG. 4 shows the frequency of abnormal blood urea nitrogen of mice at zero, three, and five days after the administration of 14 mg/kg of cisplatin; 207 mg of MK-containing sustained release capsules were intraperitoneally implanted in seven mice of the MK administration group , and 207 mg of physiological saline-containing sustained release capsules were intraperitoneally implanted in seven mice of the physiological saline administration group. The frequency of abnormality indicates the rate of occurrence of BUN abnormality when 50 BUN or more is the abnormal-level.

EXAMPLE 2 Effect of MK on Relieving Hepatopathy

Wild mice with acute hepatopathy caused by carbon tetrachloride were prepared. The effects of administering MK on relieving acute hepatopathy were then monitored. Five mice were employed for each treatment. Once carbon tetrachloride diluted to 10% with food oil “Medium Chain Triglyceride: Panasate 800” (NOF corporation) were administered to the mice, they were fasted. Physiological saline, 0.017 mg of MK or 1.7 mg of MK (JP-A No. Hei 9-95454), was administered intraperitoneally after 24 hours and again 8 hours after the first administration. Blood was collected after 16 hours, and serum GOT and GPT were measured (FIGS. 5 and 6).

The Student t test revealed that the GOT of the physiological saline group did not significantly differ from that of the MK (1.7 mg) administration group as shown in FIGS. 5 and 6. In contrast, GPT between the groups differed significantly at the 5% risk level. It was thus determined that MK significantly relieved acute hepatopathy caused by carbon tetrachloride.

EXAMPLE 3 Effect of MK on Relieving Nephropathy

G401 cells derived from human infantile renal cancer (Wilms tumor) were used considering the side effects of antitumor agent cisplatin on kidneys.

G401 cells derived from human infantile renal cancer (Wilms tumor) were adjusted to 1×10⁵ cells/ml or 3×10⁵ cells/ml by 10% FBS/DME medium. 2×10⁴ cells or 6×10⁴ cells were inoculated per well of a 96-well plate (COSTAR: 3596) and incubated at 37° C. overnight under a 5% CO₂ atmosphere.

Subsequently, the cells were incubated in a 0.1% FBS/DME medium containing 2 μg/ml or 10 μg/ml of MK and in the same medium without MK as a control group for six hours. After the second incubation, the cells were incubated in a medium containing 10 μM of cisplatin (product name, briplatin, Bristol Myers Squibb Company) for 2 hours.

The cultured media were washed four times after the incubation, and the cell incubation was continued in a media containing 2 μg/ml or 10 μg/ml of MK the same as above.

Proliferation activity of the live cells was measured with Premix WST-1 Cell Proliferation Assay System (Takara) to evaluate the effect of MK on relieving nephropathy. Proliferation activity was assayed by intracellular division and proliferation of mitochondria reflected in absorbance (450 nm, control: 655 nm) in the same way as in an MTT assay.

Specifically, the cells were treated by cisplatin. Premix WST-1 reagent, up to {fraction (1/10)} of the medium, was then added to each well on the second, third, or fourth day after the cispaltin treatment, and the cells were incubated for 4 hours. The absorbance of each well was measured with a Plate Reader (BIO-RAD; Model 3550) (FIGS. 7 and 8). FIGS. 7 and 8 indicate that 2 to 10 μg/ml of MK dramatically decreased the number of G401 cell deaths due to cisplatin (antitumor agent) nearly two fold.

EXAMPLE 4 Effect of PTN on Relieving Drug-Induced Nephropathy

ICR mice (male, 8 to 10 week-old) were divided into two groups; one for physiological saline administration and the other for PTN administration (11 mice each). The dosages of PTN and physiological saline were 500 μg/kg for each group (Merenmies, J. and H. Rauvala: J. Biol. Chem. 265: 16721-16724, 1990). Briplatin (Bristol Myers Squibb Company) was used as cisplatin.

PTN or physiological saline was administered intraperitoneally to each mouse of the above two groups for three days continuously. On the fourth day, whole blood was collected from three mice of each group, and serum was prepared to serve as the serum sample before the administration of briplatin.

In the afternoon of the same day (the fourth day), 15 mg/kg of briplatin was intraperitoneally administered to each of the rest of mice. PTN or physiological saline was continuously administered to the rest of mice on each day until the seventh day. On the sixth and eighth days, whole blood was collected from the mice, and the serum was prepared to serve as the serum sample on the second and fourth days after the administration of briplatin.

Blood urea nitrogen (BUN), a representative marker of renal function, (FIG. 9) and serum creatinine (FIG. 10) of each sample were measured by Iatro-chrom UN (IATRON LABORATORIES, INC.) and Creatinine-test Wako (Wako Pure Chemical Industries, Ltd.), respectively. FIGS. 9 and 10 show that BUN and creatinine in the physiological saline administration group tended to be higher than that in the PTN administration group. These results indicate that both PTN and MK relieve drug-induced nephropathy.

Industrial Applicability

The present invention demonstrates that the MK family proteins effectively relieve drug-induced nephropathy and hepatopathy. Therefore, pharmaceutical composition of the invention, comprising MK family protein as an effective ingredient, is useful for relieving nephropathy and hepatopathy induced by drugs, especially antitumor agents.

9 1 168 PRT Homo sapiens 1 Met Gln Ala Gln Gln Tyr Gln Gln Gln Arg Arg Lys Phe Ala Ala Ala 1 5 10 15 Phe Leu Ala Phe Ile Phe Ile Leu Ala Ala Val Asp Thr Ala Glu Ala 20 25 30 Gly Lys Lys Glu Lys Pro Glu Lys Lys Val Lys Lys Ser Asp Cys Gly 35 40 45 Glu Trp Gln Trp Ser Val Cys Val Pro Thr Ser Gly Asp Cys Gly Leu 50 55 60 Gly Thr Arg Glu Gly Thr Arg Thr Gly Ala Glu Cys Lys Gln Thr Met 65 70 75 80 Lys Thr Gln Arg Cys Lys Ile Pro Cys Asn Trp Lys Lys Gln Phe Gly 85 90 95 Ala Glu Cys Lys Tyr Gln Phe Gln Ala Trp Gly Glu Cys Asp Leu Asn 100 105 110 Thr Ala Leu Lys Thr Arg Thr Gly Ser Leu Lys Arg Ala Leu His Asn 115 120 125 Ala Glu Cys Gln Lys Thr Val Thr Ile Ser Lys Pro Cys Gly Lys Leu 130 135 140 Thr Lys Pro Lys Pro Gln Ala Glu Ser Lys Lys Lys Lys Lys Glu Gly 145 150 155 160 Lys Lys Gln Glu Lys Met Leu Asp 165 2 168 PRT Mus sp. 2 Met Ser Ser Gln Gln Tyr Gln Gln Gln Arg Arg Lys Phe Ala Ala Ala 1 5 10 15 Phe Leu Ala Leu Ile Phe Ile Leu Ala Ala Val Asp Thr Ala Glu Ala 20 25 30 Gly Lys Lys Glu Lys Pro Glu Lys Lys Val Lys Lys Ser Asp Cys Gly 35 40 45 Glu Trp Gln Trp Ser Val Cys Val Pro Thr Ser Gly Asp Cys Gly Leu 50 55 60 Gly Thr Arg Glu Gly Thr Arg Thr Gly Ala Glu Cys Lys Gln Thr Met 65 70 75 80 Lys Thr Gln Arg Cys Lys Ile Pro Cys Asn Trp Lys Lys Gln Phe Gly 85 90 95 Ala Glu Cys Lys Tyr Gln Phe Gln Ala Trp Gly Glu Cys Asp Leu Asn 100 105 110 Thr Ala Leu Lys Thr Arg Thr Gly Ser Leu Lys Arg Ala Leu His Asn 115 120 125 Ala Glu Cys Gln Lys Thr Val Thr Ile Ser Lys Pro Cys Gly Lys Leu 130 135 140 Thr Lys Pro Lys Pro Gln Ala Glu Ser Lys Lys Lys Lys Lys Glu Gly 145 150 155 160 Lys Lys Gln Glu Lys Met Leu Asp 165 3 168 PRT Rattus sp. 3 Met Ser Ser Gln Gln Tyr Gln Gln Gln Arg Arg Lys Phe Ala Ala Ala 1 5 10 15 Phe Leu Ala Leu Ile Phe Ile Leu Ala Ala Val Asp Thr Ala Glu Ala 20 25 30 Gly Lys Lys Glu Lys Pro Glu Lys Lys Val Lys Lys Ser Asp Cys Gly 35 40 45 Glu Trp Gln Trp Ser Val Cys Val Pro Thr Ser Gly Asp Cys Gly Leu 50 55 60 Gly Thr Arg Glu Gly Thr Arg Thr Gly Ala Glu Cys Lys Gln Thr Met 65 70 75 80 Lys Thr Gln Arg Cys Lys Ile Pro Cys Asn Trp Lys Lys Gln Phe Gly 85 90 95 Ala Glu Cys Lys Tyr Gln Phe Gln Ala Trp Gly Glu Cys Asp Leu Asn 100 105 110 Thr Ala Leu Lys Thr Arg Thr Gly Ser Leu Lys Arg Ala Leu His Asn 115 120 125 Ala Glu Cys Gln Lys Thr Val Thr Ile Ser Lys Pro Cys Gly Lys Leu 130 135 140 Thr Lys Pro Lys Pro Gln Ala Glu Ser Lys Lys Lys Lys Lys Glu Gly 145 150 155 160 Lys Lys Gln Glu Lys Met Leu Asp 165 4 168 PRT Bos sp. 4 Met Gln Thr Pro Gln Tyr Leu Gln Gln Arg Arg Lys Phe Ala Ala Ala 1 5 10 15 Phe Leu Ala Phe Ile Phe Ile Leu Ala Ala Val Asp Thr Ala Glu Ala 20 25 30 Gly Lys Lys Glu Lys Pro Glu Lys Lys Val Lys Lys Ser Asp Cys Gly 35 40 45 Glu Trp Gln Trp Ser Val Cys Val Pro Thr Ser Gly Asp Cys Gly Leu 50 55 60 Gly Thr Arg Glu Gly Thr Arg Thr Gly Ala Glu Cys Lys Gln Thr Met 65 70 75 80 Lys Thr Gln Arg Cys Lys Ile Pro Cys Asn Trp Lys Lys Gln Phe Gly 85 90 95 Ala Glu Cys Lys Tyr Gln Phe Gln Ala Trp Gly Glu Cys Asp Leu Asn 100 105 110 Thr Ala Leu Lys Thr Arg Thr Gly Ser Leu Lys Arg Ala Leu His Asn 115 120 125 Ala Glu Cys Gln Lys Thr Val Thr Ile Ser Lys Pro Cys Gly Lys Leu 130 135 140 Thr Lys Ser Lys Pro Gln Ala Glu Ser Lys Lys Lys Lys Lys Glu Gly 145 150 155 160 Lys Lys Gln Glu Lys Met Leu Asp 165 5 135 PRT Gallus sp. 5 Gly Lys Lys Glu Lys Pro Glu Lys Lys Ala Lys Lys Ser Asp Cys Gly 1 5 10 15 Glu Trp Gln Trp Ser Val Cys Val Pro Thr Asn Gly Asp Cys Gly Leu 20 25 30 Gly Thr Arg Glu Gly Thr Arg Thr Gly Ala Glu Cys Lys Gln Thr Thr 35 40 45 Lys Thr Gln Lys Cys Lys Ile Pro Cys Asn Trp Lys Lys Gln Phe Gly 50 55 60 Ala Glu Cys Lys Tyr Gln Phe Gln Ala Trp Gly Glu Cys Asp Leu Asn 65 70 75 80 Thr Ala Leu Lys Thr Arg Thr Gly Asn Leu Lys Arg Ala Leu His Asn 85 90 95 Ala Glu Cys Gln Lys Thr Val Thr Ile Ser Lys Pro Cys Gly Lys Leu 100 105 110 Thr Lys Pro Lys Pro Gln Glx Glu Lys Lys Lys Lys Lys Glu Gly Lys 115 120 125 Lys Gln Glu Lys Met Leu Asx 130 135 6 143 PRT Homo sapiens 6 Met Gln His Arg Gly Phe Leu Leu Leu Thr Leu Leu Ala Leu Leu Ala 1 5 10 15 Leu Thr Ser Ala Val Ala Lys Lys Lys Asp Lys Val Lys Lys Gly Gly 20 25 30 Pro Gly Ser Glu Cys Ala Glu Trp Ala Trp Gly Pro Cys Thr Pro Ser 35 40 45 Ser Lys Asp Cys Gly Val Gly Phe Arg Glu Gly Thr Cys Gly Ala Gln 50 55 60 Thr Gln Arg Ile Arg Cys Arg Val Pro Cys Asn Trp Lys Lys Glu Phe 65 70 75 80 Gly Ala Asp Cys Lys Tyr Lys Phe Glu Asn Trp Gly Ala Cys Asp Gly 85 90 95 Gly Thr Gly Thr Lys Val Arg Gln Gly Thr Leu Lys Lys Ala Arg Tyr 100 105 110 Asn Ala Gln Cys Gln Glu Thr Ile Arg Val Thr Lys Pro Cys Thr Pro 115 120 125 Lys Thr Lys Ala Lys Ala Lys Ala Lys Lys Gly Lys Gly Lys Asp 130 135 140 7 140 PRT Mus sp. 7 Met Gln His Arg Gly Phe Phe Leu Leu Ala Leu Leu Ala Leu Leu Val 1 5 10 15 Val Thr Ser Ala Val Ala Lys Lys Lys Glu Lys Val Lys Lys Gly Ser 20 25 30 Glu Cys Ser Glu Trp Thr Trp Gly Pro Cys Thr Pro Ser Ser Lys Asp 35 40 45 Cys Gly Met Gly Phe Arg Glu Gly Thr Cys Gly Ala Gln Thr Gln Arg 50 55 60 Val His Cys Lys Val Pro Cys Asn Trp Lys Lys Glu Phe Gly Ala Asp 65 70 75 80 Cys Lys Tyr Lys Phe Glu Ser Trp Gly Ala Cys Asp Gly Ser Thr Gly 85 90 95 Thr Lys Ala Arg Gln Gly Thr Leu Lys Lys Ala Arg Tyr Asn Ala Gln 100 105 110 Cys Gln Glu Thr Ile Arg Val Thr Lys Pro Cys Thr Ser Lys Thr Lys 115 120 125 Ser Lys Thr Lys Ala Lys Lys Gly Lys Gly Lys Asp 130 135 140 8 142 PRT Gallus sp. 8 Met Gln Pro Arg Gly Leu Leu Leu Leu Leu Ala Leu Leu Leu Leu Ala 1 5 10 15 Ala Ala Ala Glu Ala Ala Lys Ala Lys Lys Glu Lys Met Lys Lys Glu 20 25 30 Gly Ser Glu Cys Gln Asp Trp His Trp Gly Pro Cys Ile Pro Asn Ser 35 40 45 Lys Asp Cys Gly Leu Gly Tyr Arg Glu Gly Ser Cys Gly Asp Glu Ser 50 55 60 Arg Lys Leu Lys Cys Lys Ile Pro Cys Asn Trp Lys Lys Lys Phe Gly 65 70 75 80 Ala Asp Cys Lys Tyr Lys Phe Glu Ser Trp Gly Gly Cys Ser Ala Lys 85 90 95 Thr Gly Val Lys Thr Arg Ser Gly Ile Leu Lys Lys Ala Leu Tyr Asn 100 105 110 Ala Glu Cys Glu Glu Val Val Tyr Val Ser Lys Pro Cys Thr Ala Lys 115 120 125 Met Lys Ala Lys Ala Lys Ala Lys Lys Gly Lys Gly Lys Asp 130 135 140 9 142 PRT Xenopus laevis 9 Met Glu Leu Arg Ala Phe Cys Val Ile Leu Leu Ile Thr Val Leu Ala 1 5 10 15 Val Ser Ser Gln Ala Ala Lys Asn Lys Lys Glu Lys Gly Lys Lys Gly 20 25 30 Ala Ser Asp Cys Thr Glu Trp Thr Trp Gly Ser Cys Ile Phe Asn Ser 35 40 45 Lys Asp Cys Gly Ala Gly Thr Arg Glu Gly Thr Cys Lys Glu Glu Thr 50 55 60 Arg Lys Leu Lys Cys Lys Ile Leu Cys Asn Thr Lys Lys Ala Phe Gly 65 70 75 80 Ala Asp Cys Lys Tyr Lys Phe Glu Asn Thr Gly Glu Cys Asn Ala Thr 85 90 95 Thr Gly Asn Lys Val Arg Ser Gly Thr Leu Lys Lys Ala Leu Tyr Asn 100 105 110 Ala Asp Cys Gln Gln Thr Val Glu Ala Thr Lys Pro Cys Ser Leu Lys 115 120 125 Thr Lys Ser Lys Ser Lys Gly Lys Lys Gly Lys Gly Lys Glu 130 135 140 

What is claimed is:
 1. A method for suppressing or treating nephropathy induced by cisplatin or an antitumor agent that acts by the same mechanism as cisplatin, wherein the method comprises administering midkine (MK) or pleiotropin (PTN) protein to a mammal.
 2. The method according to claim 1, wherein said nephropathy is induced by cisplatin.
 3. The method according to claim 1, wherein said nephropathy is acute renal failure.
 4. The method according to claim 1, wherein said mechanism comprises cross-linking DNA. 